diff --git a/README b/README
index 228120c..4b10d66 100644
--- a/README
+++ b/README
@@ -16,6 +16,9 @@ modulization
     clean source
 debouncing
 anti-ghost
+sleep&wakeup
+boot keyboard support
+mouse key
 keymap layer
     key combination switch
     toggle siwtch
@@ -24,6 +27,7 @@ setting menu(wizard)
     debug console
     keymap setting
     matrix display
+PS/2 keyboard mode
 HHKB support
 Trackpoint(PS/2) support
     Thinkpad keyboard support
diff --git a/matrix.c b/matrix.c
index fc975a8..6129f52 100644
--- a/matrix.c
+++ b/matrix.c
@@ -7,38 +7,36 @@
 #include "matrix.h"
 #include "print.h"
 
+// matrix is active low. (key on: 0/key off: 1)
+// row: Hi-Z(unselected)/low output(selected)
+//      PD:0,1,2,3,6,7/PC:6,7/PF:7
+// col: input w/pullup
+//      PB:0-8
+
+// matrix state buffer
 uint8_t *matrix;
-uint8_t *prev_matrix;
+uint8_t *matrix_prev;
 static uint8_t _matrix0[MATRIX_ROWS];
 static uint8_t _matrix1[MATRIX_ROWS];
 
 static uint8_t read_col(void);
+static void unselect_rows(void);
 static void select_row(uint8_t row);
 
 
+// this must be called once before matrix_scan.
 void matrix_init(void)
 {
-    // Column: input w/pullup
+    // initialize row and col
+    unselect_rows();
     DDRB = 0x00;
     PORTB = 0xFF;
 
-    // Row: Hi-Z(unselected)
-    // PD:0,1,2,3,6,7
-    // PC:6,7
-    // PF:7
-    DDRD = 0x00;
-    PORTD = 0x00;
-    DDRC = 0x00;
-    PORTC = 0x00;
-    DDRF = 0x00;
-    PORTF = 0x00;
-
-    for (int i=0; i < MATRIX_ROWS; i++) {
-        _matrix0[i] = 0xFF;
-        _matrix1[i] = 0xFF;
-    }
+    // initialize matrix state: all keys off
+    for (int i=0; i < MATRIX_ROWS; i++) _matrix0[i] = 0xFF;
+    for (int i=0; i < MATRIX_ROWS; i++) _matrix1[i] = 0xFF;
     matrix = _matrix0;
-    prev_matrix = _matrix1;
+    matrix_prev = _matrix1;
 }
 
 uint8_t matrix_scan(void)
@@ -46,25 +44,65 @@ uint8_t matrix_scan(void)
     uint8_t row, state;
     uint8_t *tmp;
 
-    tmp = prev_matrix;
-    prev_matrix = matrix;
+    tmp = matrix_prev;
+    matrix_prev = matrix;
     matrix = tmp;
 
     for (row = 0; row < MATRIX_ROWS; row++) {
         select_row(row);
         _delay_us(30);  // without this wait read unstable value.
         state = read_col();
+        unselect_rows();
 
         matrix[row] = state;
     }
     return 1;
 }
 
+bool matrix_is_modified(void) {
+    for (int i=0; i <MATRIX_ROWS; i++) {
+        if (matrix[i] != matrix_prev[i])
+            return true;
+    }
+    return false;
+}
+
+bool matrix_has_ghost(void) {
+    for (int i=0; i <MATRIX_ROWS; i++) {
+        if (matrix_has_ghost_in_row(i))
+            return true;
+    }
+    return false;
+}
+
+bool matrix_has_ghost_in_row(uint8_t row) {
+    uint8_t state = ~matrix[row];
+    // no ghost exists in case less than 2 keys on
+    if (((state - 1) & state) == 0)
+        return false;
+
+    // ghost exists in case same state as other row
+    for (int i=0; i < MATRIX_ROWS; i++) {
+        if (i == row) continue;
+        if ((~matrix[i] & state) == state) return true;
+    }
+    return false;
+}
+
 static uint8_t read_col(void)
 {
     return PINB;
 }
 
+static void unselect_rows(void) {
+    DDRD  = 0x00;
+    PORTD = 0x00;
+    DDRC  = 0x00;
+    PORTC = 0x00;
+    DDRF  = 0x00;
+    PORTF = 0x00;
+}
+
 static void select_row(uint8_t row)
 {
     switch (row) {
diff --git a/matrix.h b/matrix.h
index 6624215..d529091 100644
--- a/matrix.h
+++ b/matrix.h
@@ -1,6 +1,10 @@
+#include <stdbool.h>
 
 extern uint8_t *matrix;
-extern uint8_t *prev_matrix;
+extern uint8_t *matrix_prev;
 
 void matrix_init(void);
 uint8_t matrix_scan(void);
+bool matrix_is_modified(void);
+bool matrix_has_ghost(void);
+bool matrix_has_ghost_in_row(uint8_t row);
diff --git a/mykey.c b/mykey.c
index 93f753f..b22c68f 100644
--- a/mykey.c
+++ b/mykey.c
@@ -24,10 +24,12 @@
  * THE SOFTWARE.
  */
 
+#include <stdbool.h>
 #include <avr/io.h>
 #include <avr/pgmspace.h>
 #include <avr/interrupt.h>
 #include <util/delay.h>
+
 #include "usb_keyboard_debug.h"
 #include "print.h"
 #include "matrix.h"
@@ -45,7 +47,8 @@ uint16_t idle_count=0;
 
 int main(void)
 {
-    uint8_t modified = 0;
+    bool modified = false;
+    bool has_ghost = false;
     uint8_t key_index = 0;
 
     // set for 16 MHz clock
@@ -77,55 +80,40 @@ int main(void)
     while (1) {
         uint8_t row, col, code;
 
-        modified = 0;
-
         matrix_scan();
 
-        keyboard_modifier_keys = 0;
-        for (int i = 0; i < 6; i++)
-            keyboard_keys[i] = KB_NO;
-        key_index = 0;
+        modified = matrix_is_modified();
+        has_ghost = matrix_has_ghost();
 
-        for (row = 0; row < MATRIX_ROWS; row++) {
-            if (matrix[row] != prev_matrix[row]) {
-                modified = 1;
-            }
+        // doesnt send keys during ghost occurs
+        if (modified && !has_ghost) {
+            key_index = 0;
+            keyboard_modifier_keys = 0;
+            for (int i = 0; i < 6; i++) keyboard_keys[i] = KB_NO;
 
-            for (col = 0; col < MATRIX_COLS; col++) {
-                if (matrix[row] & 1<<col) continue;
-                code = get_keycode(row, col);
-                
-                // Modifier keycode: 0xE0-0xE7
-                if (KB_LCTRL <= code && code <= KB_RGUI) {
-                    keyboard_modifier_keys |= 1<<(code&0x07);
-                } else {
-                    if (key_index < 6) {
-                        keyboard_keys[key_index] = code;
-                    }
-                    key_index++;
-                }
-
-            }
-        }
-
-        if (key_index > 6) {
-            //Rollover
-        }
-                
-
-
-        // if any keypresses were detected, reset the idle counter
-        if (modified) {
-            print("    01234567\n");
             for (row = 0; row < MATRIX_ROWS; row++) {
-                phex(row); print(": "); pbin_reverse(matrix[row]); print("\n");
+                for (col = 0; col < MATRIX_COLS; col++) {
+                    if (matrix[row] & 1<<col) continue;
+
+                    code = get_keycode(row, col);
+                    if (KB_LCTRL <= code && code <= KB_RGUI) {
+                        // modifier keycode: 0xE0-0xE7
+                        keyboard_modifier_keys |= 1<<(code & 0x07);
+                    } else {
+                        if (key_index < 6)
+                            keyboard_keys[key_index] = code;
+                        key_index++;
+                    }
+                }
             }
-            print("keys: ");
-            for (int i = 0; i < 6; i++) { phex(keyboard_keys[i]); print(" "); }
-            print("\n");
-            print("mod: "); phex(keyboard_modifier_keys); print("\n");
+
+            if (key_index > 6) {
+                //Rollover
+            }
+
             usb_keyboard_send();
 
+
             // variables shared with interrupt routines must be
             // accessed carefully so the interrupt routine doesn't
             // try to use the variable in the middle of our access
@@ -134,6 +122,23 @@ int main(void)
             sei();
         }
 
+        // print matrix state for debug
+        if (modified) {
+            print("r/c 01234567\n");
+            for (row = 0; row < MATRIX_ROWS; row++) {
+                phex(row); print(": ");
+                pbin_reverse(matrix[row]);
+                if (matrix_has_ghost_in_row(row)) {
+                    print(" <ghost");
+                }
+                print("\n");
+            }
+            print("keys: ");
+            for (int i = 0; i < 6; i++) { phex(keyboard_keys[i]); print(" "); }
+            print("\n");
+            print("mod: "); phex(keyboard_modifier_keys); print("\n");
+        }
+
         // now the current pins will be the previous, and
         // wait a short delay so we're not highly sensitive
         // to mechanical "bounce".